Chip detector



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ATTDRNEY June l2, 1951 H. HARlsoN CHIP DETEcToR Filed oct. 1, 1949 N. me ,MR ER VA mH V. m M ZM 8 260 l w w f a 44M 5 f 2 5 2 vw l ,l 2 a, a 2 44 2 23 04 c i. M

Patented `une 12, 1951 CHIP DETECTOR Harry Harrison, Fair Lawn, N. J., assigner to Wright Aeronautical Corporation, a corporation of New York Application Gctober 1, 1949, Serial No. 119,176 n (Cl. 20G-53) Claims.

This invention relates to apparatus for detecting the presence, within an engine, of chips or pieces broken olf parts of the engine thereby providing a warning that some part of the engine may be about to fail. Such apparatus is known as a chip detector.

Aircraft engines are commonly equipped with a chip detector in order to provide a Warning of possible incipient engine failure. Such detectors generally comprise a plug located at the lower-most portion of the engine housing or sump or at some other location where chips from engine parts will settle. This plug is provided with a central electric contact spaced and insulated from the engine housing. An electric circuit including a warning signal is connected or'is adapted to be connected between said central contact and the adjacent portion of the engine housing so that when said circuit is so connected the warning signal is energized if a metal piece or pieces should bridge the gap between said central contact and the adjacent portion of the engine housing. The electric Warning signal circuit can either form part of the aircraft installation or said circuit may be portable and adapted to be connected to the chip detector plug when the aircraft engine is being checked after or prior to a flight.

During engine operation small or iine metal particles normally wear off from relatively moving engaging engine parts, but the gap between said central electrode of the chip detecting plug and the adjacent housing portion is suiciently large that these fine particles are too small to bridge said gap to complete the electric circuit connected thereacross. When a large piece or chip breaks oli a part of the engine it will bridge said gap and when said circuit is connected across said gap the Warning signal will be operated. It frequently is the case, however, that said signal is operated not because a large piece or chip has broken ofi an engine part but because the line particles, resulting from normal engine wear, having accumulated at the chip detecting plug to such an extent as to bridge said gap whereupon said Warning signal circuit will be energized to give a false indication of the presence of a chip. In either case if the Warning signal operates, the chip detecting plug is removed while the aircraft engine is on vthe ground in order to determine the cause of the signal. When the plug is removed all the oil in the engine housing is lost. This is particularly wasteful if the warning signal energization is caused only by the accumulation of fine particles chip detecting structure comprises two parts, a

rst tubular part adapted to be removably secured to the engine over a hole in the engine..

housing at which chips are apt to collect and a second part or plug for closing the outer end of said tubular part. In addition a valve is provided for closing the inner end of the tubular part when said plug is removed, said valve being mechazn'caliy moved to its open position by an electric contact on said plug when said plug is being secured in position on the tubular member and said valve and plug contact both functioning as chip detecting electrodes. With this arrangement when the chip detecting plug is removed in order to determine the cause of an operation of the chip detecting warning signal the valve closes to prevent loss of engine oil.

Other objects of the invention will become apparent upon reading the annexed detailed description in connection with the drawing in,

which:

Figure 1 is a sectional view through a chip detecting plug structure embodying the invention,

Figure 2 is a sectional View taken along line 2-2 of Figure 1; and

Figure 3 is a sectional view illustrating oil draining apparatus for use with the chip detecting structure of Figures l and 2.

Referring first to Figures 1 and 2 of the drawing, an engine housing or sump for the engine lubricating oil is indicated in part at I0, said housing being of metallic material and having an opening I2 at its lower-most portion or at some other point at which chips breaking olf engine parts are apt to collect. The opening I2 is threaded as indicated at I4. A hollow metallic tubular member I 6 is screwed into the tapped hole I2, said tubular member having an internal shoulder I8 intermediate its ends and, facing the outer end of said member. In addition the bore of said tubular member between its shoulder I8 and its inner end comprises a conical surface 20 ilaring or increasing in diameter toward said inner end. A valve guide 22 of electric insulating material is iitted within the tubular member I6 against the shoulder I8, said valve guide having openings 24 therethrough to provide substantially unrestricted communication between the ends of said tubular member. ber 26 is provided with a stem 28 slidably received in the valve guide 22. The head of the valve 25 has a conical valve seat portion 30 tapering to- A valve mem-- ward the valve stem 28 and adapted to seat against the conical surface 2G to close the opening l2. In addition the tip or inner end of the valve head comprises a conical portion 32 with its apex directed inwardly into the engine housing l0. A valve spring 34 is disposed between the valve guide 22 and a pin 36 extending through and carried by the valve stem 28, said spring urging the valve 2E toward its closed position.

The outer end of the tubular member I5 is provided with internal threads 38, similar to the threads l of the opening I2 in the engine housing, and a plug 49 is screwed into the outer end of the tubular member l5 to close the outer end of said member. The body of the plug d is metallic and hollow with a conical recess 42 at its inner end aring or increasing in diameter toward the interior of the engine housing. A collar i4 of electric insulating material is held against a shoulder 45 in the plug 40 by a nut d8 and an electrode 55 extends centrally through the insulating collar 44. The electrode 50 has a conical head portion at its inner end and its outer end extends through the insulating collar 3d and is screwed into an electric contact member 52. A gasket 54 is disposed between the head of the electrode 5G and the insulating collar 44 to prevent leakage of engine lubricating oil out between said electrode and collar. A sleeve 55 of electric insulating material is disposed between the ciectric contact member 52 and the nut 45, said sleeve being held in position by an inturned flange 5t formed at the outer end of the nut 48.

The conical head of the electrode 5@ has its apex or tip end directed inwardly into the enn gine housing and said tip end is received within a recess in the adjacent end or" the Valve stem 28 As illustrated, when the plug le is screwed into position on the tubular member l5, the tip of the electrode 55 is received within the recess in the valve stem 2S to move and hold the valve 26 open against the spring 34. At the same time, engagement oi the electrode 5S with the valve stem 2S provides an electric connection therebetween. When the plug 4i? is removed from the tubular member I6, the spring 34 automatically closes the valve 26 to prevent loss of lubricating oil from the engine out through the opening l2. As illustrated in Figure i, the dimensions are such that the valve 25 closes before the plug 45 is completely unscrewed from the tubular member i5.

An electric circuit 51 is connected or is adapted to be connected to the plug d. As schematically illustrated in Figure i, the circuit 5-1 connected to the plug ,d comprises a signal 5S, a source or electric energy 6i) and a switch 62 with one side of said circuit connected to the electric contact member 52 and with the other side of said circuit connected to the nut ii of the plug 15. The signal 58 may comprise an electric lamp, a buzzer, orlany other electrically operable indicator. The electric circuit l' may form part oi the engine installation with the signal 53 disposed in the pilots cockpit or a mechanic in checking the engine may connect the circuit 5i' to the plug 45.

With the riore-described construction of Figures 1 and 2, when the switch @2 is closed the signal 58 will be energized by any meta-i piece or pieces bridging the fluid gap between the electrode 55 and the adjacent surface portion di! of the plug 5D. Such a piece is schematically indicated by dot-and-dash lines at E4. In addition, because oi the electric connection between the electrode `58 and the valve stem 23, the signal :55

the tubular member' threads 38.

may be energized by any metal piece bridging the fluid gap between the head of the valve 25 and the adjacent portion of the engine housing l0 and/ or the adjacent portion of the tubular member i5. Such a large piece is indicated by the dot-and-dash lines at 65. Ali but very large pieces will settle down past the valve 25 to the space between the electrode 5i) and the adjacent conical surface Q2 of the plug 40.

In order to determine the cause for the energization of the signal 58 the plug d@ is removed but the tubular member H3 is left secured into the engine housing opening l2. As will generaily be the case, ii the signal 5B was energized because of a metal piece or pieces bridging the gap between the electrode 5@ and the adjacent surface portion 42 ci the plug 5B the nature of said piece or pieces can be determined upon removal of the ping 4Q. When the plug :iii is removed there is no loss of oil through the engine housing opening l2 because the valve 25 automatically closes upon removal of a plug Ii, however, the sig nal was energized because a large piece is lodged at the valve then when the plug 40 is screwed baci: into the tubular member I5 the signal 53 will be reenergized thereby indicating this fact. rThe tubular member i5 and its valve 25 may then be removed from the engine housing' noie l2 in order to determine the nature of the piece '35 causing the signal. In so doing any engine lubricating cil will drain out through the engine housing opening i'. In the vast majority of cases, however, the signal 58 will be energized because the circuit 5i is closed by a metaliic piece or pieces at the electrode 55. In general, therefore, with the chip detecting structure of Figures i and 2 no engine 1lubricating oil is lost in determining the cause of energization oi the chip warning signal 58.

If the engine housing l is full of oil when the tubular member I5 is being unscrewed from the housing opening i2, then the moment the tubular member i6 is removed from said opening l2 oil will gush through said opening. As a result the oil may splatter quite a bit and any chips such as may be lost. A more satisfactory procedure is to use the pipe and container iiiustrated in Figure 3 for emptying the engine housing Hl of oil before the tubular member i6 is removed from said housing.

As illustrated in Figure 3 a pipe 'l0 is connected at one end to a container schematically indicated at i2. The other end ci the pipe 'l0 is provided with threads 'M adapted to mate with In addition a sleeve i6 having a cross-bar 18 is welded or otherwise secured within the threaded end of the pipe "it and a conical prong i5 is secured to and eX- tends co-axiaily from the cross-bar 18.

With this construction oi Figure 3, before the tubular member i5 is removed from the engine housing i5, the pipe 'i5 is threaded into said tubular member in place of the piug itil. As a result the prong t engages the adjacent end of the valve stern Eil to open the valve 26 whereupon the oil within the engine housing ii) drains into the container i2. The tubular member i5 can then be removed from the housing lil without the aforementioned danger ci losing a chip 65 b cause oi oii gushing through the housing opening i2, Obviously the tip oi the prong should be so disposed relative to the threaded end of the pipe 'iii that vthe pipe threads "E4 will engage with the tubular member threads 38 before the prong B yopens the valve `28.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modications.

I claim as my invention:

1. A chip detector adapted to be removably secured to the housing of an engine so as to close an opening into said housing at a point at which chips from engine parts are apt to collect; said detector comprising a tubular member adapted to be removably secured to said engine housing over said opening; a valve carried by said tubular member and adapted to close to prevent flow therethrough, said valve when open being insulated from said tubular member and having a portion spaced from said tubular member and housing by a iluid gap; and a plug including a body member and an electrode carried by and electrically insulated from said body member, said plug being adapted to be removably secured to said tubular member with said electrode spaced from a Wall of at least one of said members by a iiuid gap and with said electrode engaging said valve to hold said valve open and to connect said circuit to said valve whereby said circuit can be completed by a metallic chip bridging either of said uid gaps.

2. A chip detector as recited in claim 1 and including a spring for urging said valve to its closed position.

3. A chip detector adapted to be removably secured to the housing of an engine so as to close an opening into said housing at a point at which chips from engine parts are apt to collect; said detector comprising a tubular member adapted to be removably secured to said engine housing over said opening; a valve co-axially carried by said tubular member; means providing a guide for said valve such that when open said valve is electrically insulated from said tubular member and has a portion spaced from said housing and t tubular member by a uid gap; a spring for urging said valve toward its closed position; and a plug including a body member and an electrode co-axially carried by and electrically insulated from said body member, said plug being adapted to have an electric circuit connected to said electrode and being adapted to be removably secured to said tubular member with said electrode spaced from a wall of at least one of said members by a fluid gap and with said electrode engaging said valve to hold said valve open against said spring and to connect said circuit to said valve whereby said circuit can be completed by a metallic chip bridging either of said iluid gaps.

4. A chip detector adapted to be removably secured to the housing of an engine so as to close an opening into said housing at a point in which chips from engine parts are apt to collect; said detector comprising a tubular member adapted to be removably secured to said engine housing over said opening; a valve co-aXially carried by said tubular member, said valve having a conical head portion with its apex directed into said housing and having a stem portion extending in the opposite direction; means providing a guide for said valve such that when said valve is open said valve head is electrically insulated from and is spaced from said housing and tubular member by a fluid gap; a spring for urging said valve toward its closed position; and a plug including a body member and an electrode co-axially carried by and insulated from said body member, said plug being adapted to have an electric circuit connected to said electrode and being adapted to be removably secured to said tubular member with said electrode spaced from a wall of at least one of said members by a fluid gap and with said electrode engaging said valve to hold the valve head open against said spring and to connect said circuit to said valve head whereby said circuit can be completed by a metallic chip bridging either of said iluid gaps.

5. A chip detector adapted to be removably secured to the housing of an engine so as to close an opening into said housing at a point at which chips are apt to collect; said detector comprising a tubular member adapted to be removably secured to said engine housing over said opening; a valve carried by said tubular member and adapted to close the inner end of said member;

means providing a guide for said valve such that when open said valve is electrically insulated from said tubular member' and has a portion spaced from said housing and tubular member by a fluid gap; a spring for urging said valve toward its closed position; and a plug including a body member and an electrode co-aXially carried by and electrically insulated from said body member, said plug being adapted to have an electric circuit connected to said electrode and being adapted to be removably secured to the outer end of said tubular member with said electrode having a portion spaced from a wall of at least one of said members by a fluid gap and with said electrode engaging said valve to hold said valve open against said spring and to connect said circuit to said valve whereby said circuit can be completed by a metallic chip bridging either of said fluid gaps.

HARRY HARRISON.

REFEREN CES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,446,056 Misener Feb. 20, 1923 2,252,222 Van Os Aug. 12, 1941 

